SU998860A1 - Shell thickness acousting checking method - Google Patents

Description

The invention relates to a measurement technique and can be used in measuring the varying thickness of shells subjected to the damaging effects of plasma or other high-temperature fluxes.

A pulsed ultrasonic method for measuring the thickness of the shells is known, in which ultrasonic pulses pass directly through the thickness of the measured material layer or through ultrasonic oscillation waveguides embedded in the material tl.

The disadvantage of this method is the need to emit powerful acoustic pulses into the shell when measuring the thickness of a material with a large attenuation coefficient J of ultrasonic waves, which complicates the implementation of the method and the measurement procedure.

The closest to the technical essence of the invention is a method of acoustic control of the thickness of the shells subjected to destructible exposure to high-temperature fluxes, which consists in the fact that they receive the passed through no less than

two waveguides, acoustic noise and, by their measured parameters, determine thickness 2 ..

The informative parameter is the ratio of the amplitudes of the noise transmitted through two waveguides with different transmission coefficients.

However, the well-known method HNteeT lacks the accuracy and noise immunity of the measurement, since the length of the waveguides is judged by the value of the amplitudes of the transmitted noise, to which the amplitudes of the impulse noise can be added, we create 1x in the shell with non-plasma flow.

The purpose of the invention is to increase the reliability and accuracy of control of the shell thickness.

The goal is achieved

20 by the fact that in the method of acoustic control of the thickness of the obebche, subjected to the destructive influence of high-temperature flows, which consists in receiving past

25, not less than two waveguides, acoustic noise and, according to their measured parameters, the thickness of the material is determined, waveguides with different speeds of ultrasonic oscillations are used, they are introduced into the shell

each other, and the thickness is determined by the mutual correlation function of the received signals.

Figure 1 shows a diagram of a device for implementing the method; in fig. Figure 2 shows the dependences of the traversed height of ultrasonic signals in waveguides with different distance velocities .V and V of ultrasonic waves as a function of time.

The scheme includes the test strip 1, outside, two parallel waveguides 2 and 3, which are applied to it, the propagation speeds of the ultrasonic vibrations M V2. They are chosen different in them, for example, by performing waveguides from materials with different physical constants. Electroacoustic transducers 4 and 5 are located at the ends of waveguides 2 and 3 on the side of the surface of shell 1, which are not subjected to plasma, and are connected in series to amplifiers 6 and 7 and detectors 8 and 9. The outputs of the detectors are connected to a correlator;

it is in turn connected to a counting device 11. The position 12 is indicated by the high temperature environment

From the presented dependence of the traveled distance of ultrasound signals in waveguides with different propagation speeds 1 and 2 of ultrasonic waves, depending on time, it is necessary to measure the time difference to determine direct | ultrasonic: distance signals and order definitions, wavelength 2 .- iproho these signals along waveguides 2 and 3.

The method is carried out as follows.

The acoustic oscillations excited by the high-temperature phase 12 are distributed over the waveguides 2 and 3, respectively, at the speeds and M ,. excite ultrasonic transducers 4 and 5. Electric signals from ultrasonic transducers 4 and 5 are amplified by amplifiers b and 7 and fed to detectors 8 and 9, C from the outputs of detectors 8 and 9, the envelopes of the signals E-, Ci) and i2 (t) X (- fc-t) are passed to the correlator 10, the output of which transmits the signal H (T), which is the mutual key function of the input function f (t) and

52 (-fc), proportional to the pasHQCTH of the signal delays {(-k) and fa (i), passed through waveguides 2 and 3. The calculating device 11 calculates the length of the waveguides.

The transmission coefficients of waveguides 2 and 3; depending on their length, they are chosen as equal as possible. This achieves the greatest similarity between the envelopes of acoustic noise transmitted through waveguides. Waveguides 2 and 3 differ only in the speed at which ultrasonic vibrations propagate in them. Therefore, signal 2. (-t) from ultrasonic transducer 5 will be close to signal i (t transducer 4, delayed in waveguide 2 by time interval f, which will be the longer the waveguide. Therefore, by measuring time interval T, you can determine the length of waveguides and thus the thickness of the shell.

Using the proposed method allows one to control the thickness of the shells with significantly greater reliability and accuracy, since the information parameter is the mutually correlation function of the delay time of signals transmitted through at least two waveguides with different propagation speeds.

Claims (2)

1. US Patent 3587299, cl. G 01 B 17/00, 19 € 9. 2. USSR author's certificate number 887927, cl. S 01 B 17/02, 1980 (.prototype). Vi